The most serious level of air pollution is now a red alert rather than orange, according to a new guideline released by Beijing Meteorological Bureau on Thursday, the Beijing News reported on Thursday.
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The bureau has also included PM 2.5, or airborne particles measuring 2.5 microns or less in diameter, as an element in the appraisal criteria for air quality.
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According to the revised guideline, when the PM 2.5 reading exceeds 500 and visibility is reduced to less than 5,000 meters, a red alert will be announced.
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Previously, the alerts were based only on visibility and humidity.
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The Beijing municipal government aims to decrease the average density of main air pollutants by 2 percent in 2013, according to the municipal government's annual work report released earlier this year.Â